Membrane Ig on human lymphocytes: rate of turnover of IgD and IgM on the surface of human tonsil cells

Abstract

The turnover of IgM and IgD molecules present on the membrane of human tonsil cells has been studied using immunofluorescence and peroxidase-catalyzed membrane radioiodination. With the first of the two techniques cells were treated with pronase to remove membrane immunoglobulin (mIg), placed in culture and stained at intervals to check the reappearance of membrane IgD and IgM on the cell membrane. These experiments showed that membrane IgD (in contrast to membrane IgM) are extremely susceptible to proteolysis. Furthermore, cells treated with a concentration of pronase found to be optimal to remove membrane IgM failed to re-express membrane IgD in vitro. The large majority of tonsil lymphocytes has both membrane IgM and IgD. Due to the different behavior of reappearance of the two membrane molecules after treatment with pronase, it was not possible to obtain the simultaneous re-expression of membrane IgM and IgD by the cells "stripped" with pronase. However, the two molecules were re-expressed in vitro by the cells treated with different pronase concentrations with a similar timing, i.e. 50% or more of the cells re-expressed membrane IgD and IgM after 8 h in culture. 131I-radioiodinated membrane IgD and IgM were also released from the cell surface with a similar timing, the half-life of permanence on the cell membrane being about 4 h for both molecules. These findings thus indicate that IgM and IgD molecules have a similar turnover and that a cell is capable of placing two different Ig molecules at a time on its surface.

Relationship between reduced b cell susceptibility to igm antibodies and reduced igd‐bearing b cells in patients with systemic lupus erythematosus

“…These results are consistent with the reports of other investigators that surface IgD, in contrast to surface IgM, is extremely susceptible to proteolysis (30,31 The phenomenon of loss of surface IgD from B cells has been described by several investigators to occur after stimulation of mature B cells by mitogens or antigens and is presumably the result of differentiation of B cells, which later become IgM-, IgG-, and IgA-secreting cells (20). In several recent studies, researchers have shown that spleen lymphocytes in NZB mice have markedly decreased levels of surface IgD relative to IgM (3,4,33).…”

Quantitation of Antibodies to IgM, IgD and β₂-Microglobulin in Antisera to Chronic Lymphatic Leukemia Lymphocytes

“…Previously, Finkelman et al [3] reported identical elec trophoretic mobilities in SDS-PAGE of hu man cellbound //-and ¿-chains. In contrast, Ferrarini et al [2] found slower mobilities for both cell-bound //-and ¿-chains com pared to their scrum Ig counterparts. In these experiments, the differences in mobili ty between cell-bound and secreted heavy chains were small, and although they were reproducible, only structural evidence will establish that cell-bound heavy chains are larger than the heavy chains of the secreted…”

The Novel IgD Binding Protein fromMoraxella catarrhalisInduces Human B Lymphocyte Activation and Ig Secretion in the Presence of Th2 Cytokines

“…catarrhalis is the third most frequent cause of bacterial otitis media and therefore is a major cause of disease. Significant numbers of normal IgD-secreting plasma cells have been found in human bronchus-associated lymphoid tissue and tonsils (4,5). This has been suggested to be due to the fact that the upper respiratory tract in humans is frequently colonized by strains of H. influenzae and M. catarrhalis, which exposes membrane proteins that activate IgD ϩ B lymphocytes (7).…”

“…IgD has been suggested to be involved in peripheral B cell tolerance, B cell recruitment, and secondary Ig light chain rearrangement, i.e., receptor editing, but still much of the function of IgD remains to be solved (1)(2)(3). Only trace amounts of IgD are found in serum, but significant numbers of normal IgD-secreting plasma cells have been found in human bronchus-associated lymphoid tissue and tonsils (4,5). This observation might be linked to the fact that the upper respiratory tract in humans are frequently colonized by strains of Moraxella catarrhalis and Haemophilus influenzae, which express outer membrane surface proteins that activate IgD ϩ B lymphocytes by cross-linking IgD (6,7).…”